Image Reader Shading Correction Using Cover State Feedback
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Solution Overview
Problem
Conventional image readers face issues with improper shading correction due to ambient light influence on detected black and white data, leading to inaccurate image reading results.
Innovation Solution
An image reader system that includes a reading section, a cover, a correction section, a white reference member, a detector, and a controller, which acquires and processes black and white data to minimize ambient light influence by using previous data for shading correction when current data is affected by light, ensuring accurate pixel values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If black data and white data are detected when the cover is in the open state, then the reading preparation operation can be performed earlier, but the detected data may be influenced by ambient light causing improper shading correction
Solution Approach 1:
The system performs preliminary detection of black data and white data when the cover is opened, preparing for future reading operations. This allows the reading preparation to be completed in advance, reducing the time delay when actual reading is needed, while storing the detected data for later use when conditions are appropriate
Solution Approach 2:
The system continuously monitors the cover state and uses feedback from detecting whether the cover is open or closed to determine when to acquire new black and white data. The controller adjusts the timing of data acquisition based on the cover state feedback, ensuring data is refreshed at appropriate moments while maintaining readiness for quick reading operations
2Reliability
If previous black data and white data are used when current data is influenced by ambient light, then improper shading correction is avoided, but reading accuracy may be compromised
Solution Approach 1:
The system uses feedback from the cover state detector to determine whether to use current or previous black and white data for shading correction. When the cover is closed, the system acquires fresh data; when open, it uses previously acquired data, ensuring reliability while maintaining accuracy through context-aware data selection
Solution Approach 2:
The system changes the parameter of data selection (current vs. previous black and white data) based on the cover state. This dynamic parameter adjustment allows the system to optimize between reliability and accuracy by selecting the most appropriate data set according to ambient light conditions
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively reduces ambient light influence on shading correction, resulting in improved image reading accuracy and reliability by using a combination of current and previous data for precise pixel value calculations.
Implementation Method 1
The light receiver includes a plurality of light receiving elements arranged in a line extending in a main scanning direction, the plurality of light receiving elements respectively corresponding to a plurality of pixels arranged in the line
Data Source
AI summary
In an image reader, a controller acquires a set of first black data for each pixel in a line by reading one line worth of image via a light receiver with a light source being turned off when a detector detects that a cover is in an open state. Subsequently, the controller acquires a set of white data for the each pixel in the line by reading a white reference member via the light receiver with the light source emitting light when the detector detects that the cover is in the open state. The controller calculates a set of correction data for the each pixel in the line by subtracting the set of first black data of the each pixel from the set of first white data of the each pixel. The set of correction data is used in a shading correction.